Chiwetel Ejiofor commands the screen in an epic, intimate and deeply powerful portrait of Solomon Northup, a black man sold into slavery in 19th century America. It's an account made even more striking by the fact it's based on Northup's own memoirs, brilliantly served by British director Steve McQueen (the erstwhile video artist behind Hunger and Shame) who illustrates the politics of oppression in excruciating detail, rather than preaching through his characters.

Solomon Northup is a family man and a free man - with the papers to prove it - who earns a living in New York as a carpenter and by playing the fiddle. Already, he looks incongruous, dressed like a Dickensian gentleman, moving in polite circles - a scene not often captured in period films. When he's asked to Washington for what looks like a lucrative gig, he can't pass it up, but it turns out to be a ruse. After a drug-induced sleep, he wakes up in chains.

As his captors see it (including a brief turn by Paul Giamatti playing against type), Solomon needs putting back in his place. The whip is swiftly employed whenever he mentions his freedom and in a flash, a cultured man becomes no more than cattle. The violence is starkly pictured by McQueen, lingering on black skin torn apart to reveal milky white flesh and, of course, red blood.

Those images are hugely visceral, but it's the de-socialisation of the slaves that brings home the ruthless dehumanisation (of the victims and their oppressors). Men and women are forced to bathe together, to stand together naked for inspection, then families are torn apart and sold off like so many car parts.

Benedict Cumberbatch shows some humanity as a Southern plantation owner who buys Solomon and recognises his strong intellect. He welcomes Solomon's opinion on the running of operations in spite of snarling opposition from one of his paid grunts John Tibeats (a rabid Paul Dano). However, as another slave (Adepero Oduye) points out, their 'master' is still benefitting from human misery. She hits the nail on the head when she tells Solomon he is treated "no better than prized livestock".

A line is clearly traced from Solomon's outrage and denial to his quiet acceptance, but on the matter of his spiritual defeat that line becomes blurred. Solomon is, above all, a pragmatist. He hasn't given up entirely. He lies in wait for an opportunity to get word back to his family, but until that time, his own humanity is severely tested. He is sold on to a drunken cotton grower Edwin Epps, cannily played by Michael Fassbender (McQueen's frequent collaborator) who sees himself as a victim. He consoles himself by playing his slaves off against each other, forcing a dysfunctional hierarchy.

Epps favors a pretty young slave Patsy (Lupita Nyong'o) though his affections are, for her, even harder to take than the whip. The domestic politics are further muddied by Epps's jealous, goading wife (a brittle Sarah Paulson) and Solomon is inevitably drawn into the middle of this, forced to make choices that question how far he is willing to commit to his stance of put up or shut up.

For every day that passes over the course of 12 years, Solomon is fighting a personal battle to retain some sense of himself, even after accepting a different name - Platt. For all the hostility and aggression he is daily confronted with, it is that inner turmoil that keeps you holding your breath and it is entirely palpable in a skilfully contained performance, arrestingly filmed for posterity. In all senses of the word, stunning.